The hydrogenation of polyenes to produce monoenes using ruthenium complex catalysts is disclosed in Fahey's U.S. Pat. No. 3,925,494. Fahey's U.S. Pat. No. 3,804,914, in Example II shows hydrogenation of polyenes using a ruthenium complex catalyst and excess triphenylphosphine. Fahey discloses in Journal of Organic Chemistry, Vol. 38, No. 1, 1973, pages 80-87 that Lewis Bases, including diethylamine were tested in the hydrogenation of cyclododecatriene. No bases were found to be more effective at enhancing selectivity than triphenylphosphine. No other effects were noted.
The rate of hydrogenation of a particular polyene using a ruthenium catalyst is taught to be increased by adding certain specific amines in an article titled "Selective Homogeneous Hydrogenation of 3-Oxo-1,4-diene Steroids. II. Effects of Basic Additives and para Substituents on the Hydrogenation with Dichlorotris(triphenylphosphine) ruthenium", by Nishimura et al, appearing in Bulletin of the Chemical Society of Japan, Vol. 46, 279-283 (1973).
The process disclosed by the Fahey patents suffers from the difficulty that there is an induction period of considerable length between the time the ingredients of the reaction mixture are combined under reaction conditions, and the time that the mixture actually begins to react at a significant rate.
An object of the present invention is to shorten this induction period.